xserver and mesa git update 28-12-2010

1 files changed, 200 insertions, 0 deletions

diff --git a/mesalib/src/glsl/lower_if_to_cond_assign.cpp b/mesalib/src/glsl/lower_if_to_cond_assign.cpp
new file mode 100644
index 000000000..9212ae21e
--- /dev/null
+++ b/mesalib/src/glsl/lower_if_to_cond_assign.cpp
@@ -0,0 +1,200 @@
+/*

+ * Copyright © 2010 Intel Corporation

+ *

+ * Permission is hereby granted, free of charge, to any person obtaining a

+ * copy of this software and associated documentation files (the "Software"),

+ * to deal in the Software without restriction, including without limitation

+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,

+ * and/or sell copies of the Software, and to permit persons to whom the

+ * Software is furnished to do so, subject to the following conditions:

+ *

+ * The above copyright notice and this permission notice (including the next

+ * paragraph) shall be included in all copies or substantial portions of the

+ * Software.

+ *

+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL

+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER

+ * DEALINGS IN THE SOFTWARE.

+ */

+

+/**

+ * \file lower_if_to_cond_assign.cpp

+ *

+ * This attempts to flatten if-statements to conditional assignments for

+ * GPUs with limited or no flow control support.

+ *

+ * It can't handle other control flow being inside of its block, such

+ * as calls or loops.  Hopefully loop unrolling and inlining will take

+ * care of those.

+ *

+ * Drivers for GPUs with no control flow support should simply call

+ *

+ *    lower_if_to_cond_assign(instructions)

+ *

+ * to attempt to flatten all if-statements.

+ *

+ * Some GPUs (such as i965 prior to gen6) do support control flow, but have a

+ * maximum nesting depth N.  Drivers for such hardware can call

+ *

+ *    lower_if_to_cond_assign(instructions, N)

+ *

+ * to attempt to flatten any if-statements appearing at depth > N.

+ */

+

+#include "glsl_types.h"

+#include "ir.h"

+

+class ir_if_to_cond_assign_visitor : public ir_hierarchical_visitor {

+public:

+   ir_if_to_cond_assign_visitor(unsigned max_depth)

+   {

+      this->progress = false;

+      this->max_depth = max_depth;

+      this->depth = 0;

+   }

+

+   ir_visitor_status visit_enter(ir_if *);

+   ir_visitor_status visit_leave(ir_if *);

+

+   bool progress;

+   unsigned max_depth;

+   unsigned depth;

+};

+

+bool

+lower_if_to_cond_assign(exec_list *instructions, unsigned max_depth)

+{

+   ir_if_to_cond_assign_visitor v(max_depth);

+

+   visit_list_elements(&v, instructions);

+

+   return v.progress;

+}

+

+void

+check_control_flow(ir_instruction *ir, void *data)

+{

+   bool *found_control_flow = (bool *)data;

+   switch (ir->ir_type) {

+   case ir_type_call:

+   case ir_type_discard:

+   case ir_type_loop:

+   case ir_type_loop_jump:

+   case ir_type_return:

+      *found_control_flow = true;

+      break;

+   default:

+      break;

+   }

+}

+

+void

+move_block_to_cond_assign(void *mem_ctx,

+			  ir_if *if_ir, ir_variable *cond_var, bool then)

+{

+   exec_list *instructions;

+

+   if (then) {

+      instructions = &if_ir->then_instructions;

+   } else {

+      instructions = &if_ir->else_instructions;

+   }

+

+   foreach_iter(exec_list_iterator, iter, *instructions) {

+      ir_instruction *ir = (ir_instruction *)iter.get();

+

+      if (ir->ir_type == ir_type_assignment) {

+	 ir_assignment *assign = (ir_assignment *)ir;

+	 ir_rvalue *cond_expr;

+	 ir_dereference *deref = new(mem_ctx) ir_dereference_variable(cond_var);

+

+	 if (then) {

+	    cond_expr = deref;

+	 } else {

+	    cond_expr = new(mem_ctx) ir_expression(ir_unop_logic_not,

+						   glsl_type::bool_type,

+						   deref,

+						   NULL);

+	 }

+

+	 if (!assign->condition) {

+	    assign->condition = cond_expr;

+	 } else {

+	    assign->condition = new(mem_ctx) ir_expression(ir_binop_logic_and,

+							   glsl_type::bool_type,

+							   cond_expr,

+							   assign->condition);

+	 }

+      }

+

+      /* Now, move from the if block to the block surrounding it. */

+      ir->remove();

+      if_ir->insert_before(ir);

+   }

+}

+

+ir_visitor_status

+ir_if_to_cond_assign_visitor::visit_enter(ir_if *ir)

+{

+   (void) ir;

+   this->depth++;

+   return visit_continue;

+}

+

+ir_visitor_status

+ir_if_to_cond_assign_visitor::visit_leave(ir_if *ir)

+{

+   /* Only flatten when beyond the GPU's maximum supported nesting depth. */

+   if (this->depth <= this->max_depth)

+      return visit_continue;

+

+   this->depth--;

+

+   bool found_control_flow = false;

+   ir_variable *cond_var;

+   ir_assignment *assign;

+   ir_dereference_variable *deref;

+

+   /* Check that both blocks don't contain anything we can't support. */

+   foreach_iter(exec_list_iterator, then_iter, ir->then_instructions) {

+      ir_instruction *then_ir = (ir_instruction *)then_iter.get();

+      visit_tree(then_ir, check_control_flow, &found_control_flow);

+   }

+   foreach_iter(exec_list_iterator, else_iter, ir->else_instructions) {

+      ir_instruction *else_ir = (ir_instruction *)else_iter.get();

+      visit_tree(else_ir, check_control_flow, &found_control_flow);

+   }

+   if (found_control_flow)

+      return visit_continue;

+

+   void *mem_ctx = talloc_parent(ir);

+

+   /* Store the condition to a variable so the assignment conditions are

+    * simpler.

+    */

+   cond_var = new(mem_ctx) ir_variable(glsl_type::bool_type,

+				       "if_to_cond_assign_condition",

+				       ir_var_temporary);

+   ir->insert_before(cond_var);

+

+   deref = new(mem_ctx) ir_dereference_variable(cond_var);

+   assign = new(mem_ctx) ir_assignment(deref,

+				       ir->condition, NULL);

+   ir->insert_before(assign);

+

+   /* Now, move all of the instructions out of the if blocks, putting

+    * conditions on assignments.

+    */

+   move_block_to_cond_assign(mem_ctx, ir, cond_var, true);

+   move_block_to_cond_assign(mem_ctx, ir, cond_var, false);

+

+   ir->remove();

+

+   this->progress = true;

+

+   return visit_continue;

+}